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Messier 87 - M87 - Elliptical Galaxy

M87 is a supergiant elliptical galaxy that's a prominent member of the Virgo cluster of galaxies. It's one of the largest and most luminous galaxies known and a strong source of electromagnetic radiation, particularly radio and X-ray emissions. At the centre of M87 is a supermassive black hole from which a jet of extremely energetic plasma extends outwards for at least 5,000 light-years. The galaxy is therefore an interesting object for both professional and amateur astronomers alike.

With an apparent magnitude of +8.6, M87 is the second brightest of the Virgo cluster galaxies. Only M49, at mag. +8.4, is marginally brighter. On dark moonless nights, M87 is visible with 7x50 or 10x50 binoculars, appearing as a faint hazy patch of light. This galaxy was one of eight discovered by Charles Messier on March 18, 1781. He also re-discovered fine globular cluster, M92, on the same day.

M87 lies at the heart of the Virgo cluster. It can be found by imagining a line connecting Denebola (β Leo - mag. +2.1) with Vindemiatrix (ε Vir - mag. +2.8). Just over half way along this line is M87. Faint elliptical galaxy M89 is positioned just over a degree east of M87 with the galaxy pair M84/M86 located 1.5 degrees to the northwest.

The Virgo galaxies are best seen during the months of March, April and May.

Through 80mm (3.1-inch) scopes, M87 appears as a fuzzy elliptical ball of light that's brighter towards the centre. Even with larger scopes it's essentially featureless, although much easier to detect. Its luminosity decreases from the core outwards and no distinctive dust lanes can be seen. The famous jet is far too faint to be observed with most backyard scopes, although it has been spotted with extremely large amateur reflectors under excellent conditions. However, it's much easier to image or photograph. Within the same low-power field as M87 are two fainter elliptical galaxies, NGC 4476 and NGC 4378.

M87 spans 8.3 x 6.6 arc minutes of apparent sky. It's located 53.5 million light-years away, which corresponds to a spatial diameter of 130,000 light-years. The galaxy is estimated to contain a trillion stars. To date, the only supernova recorded in M87 occurred in February 1919, but was not detected until 1922 when photographic plates were examined. The maximum brightness was estimated at magnitude +11.5.

Orbiting M87 is an extremely large number of globular clusters of which at least 12,000 have been identified. For comparison, our Milky Way galaxy contains only about 200.